Arbiters offer a small extra resource to their Parties. Each Turn they receive 3 Order Points, and each Arbiter has 3 or 4 Orders to choose from. Each Order uses between 1 and 3 Order Points, and each Arbiter has a different suite of orders they can use, although some Orders are common to two or more of them.
Orders may be a small extra 2 inch move (Motum), or a free hand to hand Attack (Opugnis; very useful for units with hard-hitting Basic Attacks). All Arbiters so far have one or both of these Orders available to them.
Figure 1: In a Party including Team Les Jaeger, The Colonel becomes an Arbiter. The Colonel uses Opugnis on Maximo Ligori who has already Activated earlier in this Turn; Maximo Ligori can now make a free Attack on Sho.
Orders are used when the Arbiter Activates, so it is important think ahead to get the best out of them; in the example above it would be more helpful if The Colonel was better positioned to Attack or Charge Sho or Janus Faith; but then again, that kind of planning ahead is true of any good strategy game isn't it?